Public health messages in the United States during the 20th century can be divided into two general categories. The policies and nutrition research of the first half of the 20th century (1900-1950) was focused on deficiency of nutrients. Research and public health policies in the second half of the 20th century (1950 - 2000) began to focus on the role of diet in chronic disease. In particular, the focus was on excessive, rather than inadequate, dietary intake.
The data in these tables come from early nutrition science research. Notice that only macronutrients are included; vitamins and some minerals were not discovered yet.
This next chart is the typical diet of middle class households in the Northeastern and Midwestern states during the Fall and Winter. The primary core foods were eaten every day, while secondary foods supplemented the primary foods. Periphery foods were not eaten as often.
Source: Robert Dirks, in press. What Americans Ate during the Gilded Age. Rowman & Littlefield.
The discovery of vitamins in food led researchers to pinpoint the causes of deficiency diseases such as pellagra, beriberi, rickets, and scurvy.
Early dietitians were also known as nutritionists or home economists. Many of these women had chemistry degrees, and worked in food labs, or schools. Their research was often published in the Journal of Home Economics.
This chart shows mean energy and macronutrient intake among adults aged 20 - 74 years using data from the National Health and Nutrition Examination Surveys (NHANES). Compare the energy and macronutrient intake from 1970 to 2000, and to the studies from the 1890s.
(Click on the image to enlarge it.)